How Much Force Can a Human Femur Withstand Before Breaking?

[jphillip]

Homework Statement

The Femur bone in the human leg has a minimum effective cross section of about 3.0 cm² How much compressible force can it withstand before breaking

Homework Equations

Compressive Strength (bone)(N/m²) = 170 x 10⁶
P = F/A

The Attempt at a Solution

Not sure what a cross section is exactly, how should A in formula Stress = F/A be written when they state 3 cm² cross section.
A = PI*R²

which one do I use for R
A = .015²
A = .03
A = .03²

170 x 10⁶ = F / .03m²

 

[Yuqing]

The A in the formula is the cross sectional area. The cross section is a "slice" of the object in question. For example, if you cut into an apple, the resulting flat shape you see would be a cross section of the apple.

 

[WatermelonPig]

3.0cm^2 * (1m/100cm)^2 = 0.0003m^2 which is the cross sectional area of the bone.